When i turn the ignition on, my horn honks
 

Hello,

Can someone advise me on what could cause my horn to go off when I turn the ignition on? The car starts and is drivable but the horn has a continuous honk.

Thanks

Hi,

remove the airbag (before that disconnect the battery and wait at least one minute) and look if something is closing the contact for the horn.
On my E46 I had a screw in there which came loose causing the car to honk randomly. Very funny :D